scholarly journals Electronic Structure of Vanadium-Doped TiO2 of Both Anatase and Rutile Based on Density Functional Theory (DFT) Approach

2018 ◽  
Vol 14 (1) ◽  
pp. 60
Author(s):  
Hari Sutrisno
Keyword(s):  
Density Functional Theory ◽  
Valence Band ◽  
Density Functional ◽  
Local Density ◽  
First Principle ◽  
High Concentration ◽  
Generalized Gradient ◽  
Functional Theory ◽  
First Principle Calculation ◽  
Intermediate Band

<p>Study of the theoretical  approah to calculate the band structure and density of states (DOS) of vanadium-doped TiO<sub>2</sub> of both anatase and rutile have been done. The first-principle calculations were done using supercell (2x1x1) method. The first-principle calculation of V-doped TiO<sub>2</sub> of both anatase and rutile were analyzed by density-functional theory (DFT) with generalized gradient approximation from Perdew-Burke-Ernzerhof (GGA+PBE), Perdew-Wang’s 1991 (GGA+PW91) and local density approximation (LDA) for exchange-correlation functionals. The calculation of electronic structures show that the V-doped TiO<sub>2</sub>-anatase with high concentration (7.93 %) in 24 atoms are direct- and indirect-gap semiconductor, whereas the V-doped TiO<sub>2</sub>-rutile with high concentration (15.79 %) in 12 atoms is direct-gap semiconductor. The V-doped TiO<sub>2</sub> of both anatase and rutile produce the intermediate bands in the upper states. Ihe V-doped anatase produces intermediate band, which is 2.05, 2.04, 2.06 eV above the valence band for GGA+PBE, GGA+PW91 and LDA, respectively. Meanwhile the V-doped rutile producesintermediate band, which is 1.76, 1.82, 1.74 eV above the valence band for GGA+PBE, GGA+PW91 and LDA, respectively.</p>

Density Functional Theory Approach for Muon Sites Estimation in Mn3Sn

2021 ◽  
Vol 1028 ◽  
pp. 199-203
Author(s):  
Fiqhri Heda Murdaka ◽  
Edi Suprayoga ◽  
Abdul Muizz Pradipto ◽  
Kohji Nakamura ◽  
Agustinus Agung Nugroho
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Full Potential ◽  
Theory Approach ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Electrostatic Potential Calculation ◽  
A Site ◽  
Linearized Augmented Plane Wave

We report the estimation of muon sites inside Mn3Sn using density functional theory based on the full-potential linearized augmented plane wave (FLAPW) calculation. Our calculation shows that the Perdew–Burke–Ernzerhof (PBE) Generalized-Gradient Approximation (GGA) functional is closer to the experimental structure compared to the von Barth-Hedin Local Density Approximation (LDA)-optimized geometry. The PBE GGA is therefore subsequently used in FLAPW post-calculation for the electrostatic potential calculation to find the local minima position as a guiding strategy for estimating the muon site. Our result reveals at least two muon sites of which one is placed at the center between two Mn-Sn triangular layers (A site) and the other at the trigonal prismatic site of Sn atom (B site). The total energy of Mn3Sn system in the presence of muon at A site or B site are compared and we find that A site is a more favorable site for muon to stop.

Electronic and geometric structure of AuxCuy clusters studied by density functional theory

2014 ◽  
Vol 25 (06) ◽  
pp. 1450011 ◽  
Author(s):  
Y. Kadioglu ◽  
O. Üzengi Aktürk ◽  
M. Tomak
Keyword(s):  
Density Functional Theory ◽  
Molecular Orbital ◽  
Density Functional ◽  
Local Density ◽  
Three Dimensional ◽  
Binding Energies ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Highest Occupied Molecular Orbital ◽  
Lowest Unoccupied Molecular Orbital

We have determined the stable structures of Au Cu n, Au 2 Cu n, Au 3 Cu n and Au x Cu 8-x clusters. It has been observed that Au Cu n, Au 2 Cu n and Au 3 Cu n systems have two-dimensional (2D) structures up to six atoms and they become three-dimensional (3D) afterwards. Au x Cu 8-x clusters favor 3D structures till the Au 7 Cu 1 cluster. We have found a lowest energy isomer of Au 6 Cu 2 from the literature. Bond lengths, binding energies, density of states (DOS), highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO-LUMO) gaps, ionization potential (IP) and electron affinity (EA) have been calculated for these structures using the first principles density functional theory (DFT) within the generalized gradient approximation (GGA) and the local density approximation (LDA). Generally, we have observed the overlap between s electrons of Cu and p electrons of Au near the Fermi level. Charge transfers are calculated by using the Löwdin analysis. It is observed that one Cu atom does not significantly modify the clusters which have more gold atoms. It is also seen that these clusters generally have nonmagnetic properties and results are consistent with the hybridization between s and d orbitals of Au in Au x Cu 8-x clusters.

Nonempirical density-functional theory for van der Waals interactions

2010 ◽  
Vol 88 (11) ◽  
pp. 1057-1062 ◽  
Author(s):  
Axel D. Becke ◽  
Alya A. Arabi ◽  
Felix O. Kannemann
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Van Der Waals ◽  
Van Der Waals Complexes ◽  
Basis Sets ◽  
Generalized Gradient ◽  
Dispersion Energy ◽  
Functional Theory ◽  
Grid Based

In previous work, Kannemann and Becke [ J. Chem. Theory Comput. 5, 719 (2009) and J. Chem. Theory Comput. 6, 1081 (2010) ] have demonstrated that the generalized gradient approximations (GGAs) of Perdew and Wang for exchange [Phys. Rev. B 33, 8800 (1986)] and Perdew, Burke, and Ernzerhof for correlation [Phys. Rev. Lett. 77, 3865 (1996)] , plus the dispersion density functional of Becke and Johnson [J. Chem. Phys. 127, 154108 (2007)] , comprise a nonempirical density-functional theory of high accuracy for thermochemistry and van der Waals complexes. The theory is nonempirical except for two universal cutoff parameters in the dispersion energy. Our calculations so far have been grid-based and have employed the local density approximation (LDA) for the orbitals. In this work, we employ orbitals from self-consistent GGA calculations using Gaussian basis sets. The results, on a benchmark set of 65 van der Waals complexes, are similar to our grid-based post-LDA results. This work sets the stage for van der Waals force computations and geometry optimizations.

Enhanced ferromagnetic properties of Cu doped two-dimensional GaN monolayer

2015 ◽  
Vol 26 (01) ◽  
pp. 1550009 ◽  
Author(s):  
Fayyaz Hussain ◽  
Y. Q. Cai ◽  
M. Junaid Iqbal Khan ◽  
Muhammad Imran ◽  
Muhammad Rashid ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Density Functional ◽  
Magnetic Coupling ◽  
First Principle ◽  
Two Dimensional ◽  
Functional Theory ◽  
Principle Calculation ◽  
First Principle Calculation ◽  
Cu Dopant

We demonstrate enhanced ferromagnetism in copper doped two-dimensional GaN monolayer ( GaN -ML). Our first principle calculation based on density functional theory predicted that nonmagnetic Cu -dopant with concentration of 6.25% to be ferromagnetic (FM) in 2D GaN layer which carries a magnetic moment of 2.0 μB per Cu atom and it is found to be long range magnetic coupling among the Cu -dopant. The Cu-dopant in 2D GaN -ML which can be explained in terms of p-d hybridization at Curie temperature and this dopant prefer the FM behavior in 2D GaN layer. Hence Cu doped 2D GaN layer shows strong magnetic properties so that it is a promising material in the field of spintronics.

Study of Structural, Electronic and Optical Properties of Lanthanum Doped Perovskite PZT Using Density Functional Theory

2017 ◽  
Vol 864 ◽  
pp. 127-132 ◽  
Author(s):  
N.H. Hussin ◽  
Mohamad Fariz Mohamad Taib ◽  
Mohd Hazrie Samat ◽  
N. Jon ◽  
Oskar Hasdinor Hassan ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Refractive Index ◽  
Optical Properties ◽  
Density Functional ◽  
Local Density ◽  
Ferroelectric Materials ◽  
Good Prediction ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Electronic And Optical Properties

Ferroelectric materials of lanthanum (La) doped PbZrTiO3 (PLZT) were investigated via first principles study. The structural, electronic and optical properties of PLZT in tetragonal structure (P4mm space group) were performed in the framework of density functional theory (DFT) with generalized gradient approximation (GGA) and local density approximation (LDA) methods. The calculated results of structural properties of PLZT were seen to be approximately close to the experimental data. The results of the electronic part were covered with the calculation of energy band gap and density of states (DOS). The highest valence band (VB) which lies at the Fermi level (EF) was dominated by the O 2p at F point. The conduction band (CB) of PLZT occurred at G point, which was primarily dominated by Ti 3d mixed at Pb and La p-state. Whereas the optical part was covered with the refractive index and absorption. The refractive index, n and the extinction coefficient, k were calculated with respect to photon energy. Those results obtained could be such a good prediction in studying parameters and properties of new materials.

scholarly journals Consistent Atomic Geometries and Electronic Structure of Five Phases of Potassium Niobate from Density-Functional Theory

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Falko Schmidt ◽  
Marc Landmann ◽  
Eva Rauls ◽  
Nicola Argiolas ◽  
Simone Sanna ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Local Density ◽  
Rhombohedral Phase ◽  
Structural Data ◽  
Potassium Niobate ◽  
Edge States ◽  
Hybrid Functional ◽  
Generalized Gradient ◽  
Functional Theory

We perform a comprehensive theoretical study of the structural and electronic properties of potassium niobate (KNbO3) in the cubic, tetragonal, orthorhombic, monoclinic, and rhombohedral phase, based on density-functional theory. The influence of different parametrizations of the exchange-correlation functional on the investigated properties is analyzed in detail, and the results are compared to available experimental data. We argue that the PBEsol and AM05 generalized gradient approximations as well as the RTPSS meta-generalized gradient approximation yield consistently accurate structural data for both the external and internal degrees of freedom and are overall superior to the local-density approximation or other conventional generalized gradient approximations for the structural characterization ofKNbO3. Band-structure calculations using a HSE-type hybrid functional further indicate significant near degeneracies of band-edge states in all phases which are expected to be relevant for the optical response of the material.

scholarly journals Effect Of Non-metal Elements (C, N, S) As Anionic Dopants On Electronic Structure Of Tio2-Anatase By Density-Functional Theory Approach

Molekul ◽  
2016 ◽  
Vol 11 (1) ◽  
pp. 33
Author(s):  
Hari Sutrisno
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Lattice Structure ◽  
Local Density ◽  
Theory Approach ◽  
Functional Theory ◽  
Intermediate Band ◽  
Doped Tio2 ◽  
Tio2 Anatase

This article is a theoritical approach to calculate the electronic structure of undoped- and non-metal anions doped-TiO2-anatase. The objective of the research is to calculate abinitio the band structure and the density of states (DOS) of undoped-, C-, N-, and S-doped TiO2-anatase. Kohn-Sham equations are performed with the density functional theory (DFT) using the local density approximation (LDA) for exchange-correlation functional. The first-principle calculations were done using supercell (2x2x1) methods as implemented within Amsterdam Density Functional (ADF)-BAND version 2014.10. The ab-initio calculation of the band structures show that all samples are direct- and indirect-gap type semiconductor. The band gap of TiO2-anatase with DFT using LDA is 2.43 eV. The addition of C atom at 0.943% in 48 atoms produces width intermediate band about 0.76 eV, which is 0.38 eV above the valence band (VB) and 1.38 eV below the conduction band (CB). The addition of N atom at 1.103% and S atom at 2.478% in the lattice structure of TiO2-anatase resulted in the addition of the VB width to 0.47 eV and 0.11 eV, while the resulting gap between the VB and the CB to 1.97 eV and 2.33 eV, respectively.

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